byAndrew Tomkins at Singularity Hub: When a small body (like an asteroid) passes close to a large body (like a planet), it gets stretched by gravity. If it gets close enough (inside a distance called the Roche limit), the small body will break apart into lots of tiny pieces and a small number of bigger pieces.
All those fragments will be jostled around and gradually evolve into a debris ring orbiting the equator of the larger body. Over time, the material in the ring will fall down to the larger body, where the larger pieces will form impact craters. These craters will be located close to the equator.
So, if Earth destroyed and captured a passing asteroid around 466 million years ago, it would explain the anomalous locations of the impact craters, the meteorite debris in sedimentary rocks, craters and tsunamis, and the meteorites’ relatively brief exposure to space radiation.
The ring would have been around the equator. And since Earth’s axis is tilted relative to its orbit around the sun, the ring would have shaded parts of Earth’s surface.
This shading in turn might have caused global cooling, as less sunlight reached the planet’s surface.
This brings us to another interesting puzzle. Around 465 million years ago, our planet began cooling dramatically. By 445 million years ago it was in the Hirnantian Ice Age, the coldest period in the past half a billion years.
Was a ring shading Earth responsible for this extreme cooling? The next step in our scientific sleuthing is to make mathematical models of how asteroids break up and disperse and how the resulting ring evolves over time. This will set the scene for climate modeling that explores how much cooling could be imposed by such a ring.
